[Feature Request] Clear notifications when adding/logging into a server fails

[simon-wilmes]

Disclaimer

• The request feature has not been addressed in the feature request list.
• The design of the feature does not require detailed discussion

Motivation

• Adding a correctly-formatted but wrong URL (no Overleaf server there) is accepted
  silently, so the user has no idea why nothing works later.
• On login failure the user only sees a generic "Login failed.", with no distinction
  between server unreachable, not an Overleaf/ShareLaTeX server, and wrong
  email/password. Network errors are swallowed entirely and produce no notification.

Feature Description

• When adding a server, do a lightweight, unauthenticated probe and, if it's
  unreachable or doesn't look like an Overleaf/ShareLaTeX server, warn with an "Add
  anyway" option (so self-hosted/offline setups aren't blocked).
• When logging in, show distinct notifications for: server unreachable, not an Overleaf
  server, and incorrect email/password.
• Keep the "is this Overleaf" detection lenient so a version change never warns on a
  working server. The probe sends no credentials, doesn't follow redirects to other
  hosts, keeps TLS verification on, and never executes server content.

[Optional] Additional context

• Applicable Overleaf Edition: Official / Community / Enterprise (Server Pro)
• Applicable Extension Range: Desktop Extension / Web Extension

[simon-wilmes]

Small real-world annoyance: I'd mistyped my own server URL and I spent a few minutes blaming my password. This shows why a connection fails (unreachable / not an Overleaf server / wrong credentials) instead of one generic message. Low priority, just a nice-to-have, I guess.

Full disclosure: generated with Claude, but I've read through and tested it against overleaf.com and my own self-hosted instance, including the failure paths. Do with that what you will.